Monday, March 16, 2015

Reminder: remove calendar stored credentials when switching HVAC modes

If you've just switched from heating to cooling (or the other way around for those down under), the first run of the system will use the calendar credentials stored by Google calendar client library in ${HOME}/.dz/calendar/StoredCredential, and your system will try to use the wrong schedule (that is, if you followed our advice and are using two different calendars for heating and cooling).

Just move that file away, or remove it altogether - DZ will present the credentials screen next time the calendar needs to be consulted.

Monday, November 17, 2014

Early Access: Google Calendar API v3 Integration

Google shut down Calendar API v2 and v1 today, replaced by v3. v3 is not a drop-in replacement for earlier versions, changes are required.


You specify credentials either as a part of configuration (permanently), or via JMX (after server startup).


First time, DZ starts an external browser with OAuth callback URL, you choose credentials to use, grant the permission to use them, DZ stores the token (not credentials) until it expires. Afterwards, calendar updater reads the token and proceeds without requiring a browser.


Get the current version from Github. Release will be following shortly.


You need to remove credentials from the configuration.


The only change you should notice is how to make DZ understand that you want to change the account associated with the calendar. Remove ${HOME}/.dz/calendar/StoredCredential file to make DZ request authentication again.

Saturday, August 16, 2014

Upcoming release: DZ 3.6.6

This is a cumulative release combining over two years of bugfixes.


  • Google Calendar access code brought to compliance with current API behavior (more secure);
  • Improved XBee devices stability, analog sensors are no longer susceptible to noise;
  • "Return to schedule" functionality is now accessible from mobile devices.

Surprisingly, there's nothing else, other than known problems (which are apparently too rare or too minor to matter).

If there is something that is bothering *you* - now is time to speak up so it gets addressed and included into this release.

Friday, November 2, 2012

Competition: Next Nest: Short Take

Lo and behold, the new Nest is here.

20% thinner.

Can't resist from thinking - when does it become so thin that oversized fingers of the contemporary user base will start smudging the walls?

On the positive note: latest version of Nest Mobile on Android doesn't require the right to discover accounts on the device. And indeed, the base layout is significantly better.

Saturday, September 1, 2012

Competition: Nest: Airwave: Fail

Spent the summer with Nest installed in my workshop for benchmarking. Whereas I'm not quite impressed with general performance, there's one thing I'm sorely disappointed with: Airwave.

Let's start with the fact that it is advertised as "an exclusive feature of Nest Learning Thermostat". Well, it's not. It existed for ages - don't know about thermostats, but one of my 10+ old HVAC units has it implemented in hardware.

Then come claims that it can "reduce A/C runtime up to 30%". I really doubt it. Except, maybe, the "up to" part - you see, technically, 1% falls under "up to 30%" as well.

Now, "I doubt it" is not a scientific proof, but here's the facts that make me come forward with this claim, and some more.

  • Under some circumstances, Airwave will backfire. Trivial example: volumetric heat capacity of the inner coil is too small for the amount of time Nest lets the air handler run. I do not know how they calculate this amount, but in either case, it fails for my specific configuration, 'cause it starts blowing warm air shortly after condenser is shut off.
  • To add insult to an injury, this makes the A/C to turn on sooner than it would otherwise have, causing short cycling.
  • Apparently, the decision to activate Airwave doesn't really take latent heat into consideration [to proper extent], and I end up with a clammy workshop which makes me put the temperature down two degrees - my normal comfortable working temperature is 28°C, but at the end of this summer, as monsoon came and brought humidity with it, I had to drop it to 26°C.
  • In addition, it appears that the inner coil's temperature rises above the dew point quite fast, and air stream starts blowing the condensate back into the air it just finished working hard on extracting humidity out of.
As a result, let me use Nests' marketspeak, "I may have ended up with electric bill up to 30% higher than last summer", when a dumb thermostat was in exactly the same location.

  • Can you fine-tune Airwave? No.
  • Can you disable Airwave? No Yes. You have to convince it first that you really want it off, Dave. (see update below)

So, either I have to put up with Nest's inefficiency, or I will have to take it off and eat the $250 + shipping as a cost of curiosity, or just sell it to someone fascinated with it. I suspect the latter will be the case, for Nest is surely falling short of its advertised virtues.

Disclaimer: The above is a personal opinion, based on subjective feelings and objective measurements. Your mileage may vary.

UPDATE (2012/10/02): Since about a couple of days ago, it is possible to disable it. However, as of the moment of writing, this is not yet reflected anywhere on Nest support site.

UPDATE (2012/10/03): Automagically, Airwave turned back on without my interference. So if it annoys you as much as it annoys me, you'll have to watch it for a while and make sure that it is really off. A similar issue came up with Auto-Away - it turns back on without being told to. Looks like a telltale sign of not saving a flag state when a device firmware update is happening.